Flow Rates Model  

The Flow Rates activity is highly recommended both for math teachers and for science teachers in all fields. It can be used effectively for a variety of content applications and at various points in a course sequence. By allowing students to practice making and testing hypotheses about liquid flowing through a simple burette, it provides an excellent introduction to the scientific method. The collection and analysis of real-time data provides students with the opportunity to use their graphing and algebra skills in a real problem-solving situation. Finally, it facilitates a direct mental mapping between students' demonstration observations and mathematical modeling.


Teacher Materials
Student Activity
Student Assessment
Learning Goals/Standards


STELLA Versions Vensim Version Web-based Simulation


  • Burette_Volume_in_ml(t) = Burette_Volume_in_ml(t - dt) + (Inflow - Outflow) * dt
  • INIT Burette_Volume_in_ml = 20
  • Inflow = 7
  • Outflow = 1.05 * sqrt(Burette_Volume_in_ml)
  • A lake or pond, fed by one river or stream, and drained by another
  • An individual cell's water balance
  • A specific organ or cavity's normal range of hydrostatic pressure (e.g., urine in a bladder)
  • An organism's overall fluid balance
  • Kinetics, relative reaction rates, and dynamic equilibrium in chemical reactions
  • Nuclear binding energy, fed by particle bombardment and drained by radioactive decay
  • How will the time needed to fill your bathtub be affected by an ill-fitting drain stopper?
  • How long will it take you to go broke if you spend more than you earn?
  • What kind of function has a rate of change which is proportional to itself?


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